Little Rock-based Alltel Corporation announced lower first-quarter earnings today but expanded its customer base. Unadjusted for one-time charges, first-quarter earnings were 61 cents per share, down from 90 cents per share in the same quarter a year ago. In the period, the company added a net of 158,000 customers. Alltel president and chief executive Scott Ford said the investment by the company in signing up the new customers will pay off in the quarters ahead. Alltel also saw earnings affected by the cost of eliminating almost 700 positions and for a building it will no longer need as a consequence. The company earned $189 million for the period ending March 31st, compared to $280 million a year before. Adjusted for restructuring charges, discontinued operations and other one-time items, Alltel earned 71 cents per share, compared to 73 cents per share a year before.